FIGS. 1a through 1d illustrate an existing technique for putting underfill resin 602 beneath the surface of a semiconductor die 601. The underfill resin 602 is placed along two adjacent edges of the semiconductor die 601 wherein the adjacent edges intersect. After a period of time has elapsed, the underfill resin 602 begins to spread by capillary effect across the under surface of the die to opposing intersecting edges until the underneath of the die is completely covered. However, the coverage of the voids (i.e. air pockets or bubbles) on the semiconductor surface is not easy to control. Further, there is a long processing time for the underfill resin to level out.
In the past, the underfill resin has been applied along two edges of a multiple edged die deeming it necessary to wait for the resin to completely spread out by capillary effect such that the underfill levels out beneath the die to substantially cover the surface underneath the die and eliminate voids. Further, there is a significant problem created when overfill occurs absent a clean up mechanism to prevent over-spreading of the underfill material.
Akram et at., disclose, in U.S. Pat. No. 6,048,656 A, issued Apr. 11, 2000, a vacuum source placed over an opening to draw underfill material in a uniform manner throughout interstices so that voids are not created. Akram et al. disclose dams disposed along multiple edges of a flip chip in order to help contain the flow of underfill material 190. Akram et al. further disclose using multiple vacuum sources and multiple injection sites to assist in the spread of underfill across the under surface of flip chip 110. Further, Akram discloses the underfill material may be inserted from an aperture in the substrate located beneath the semiconductor device.
However, Akram et al. is not directed towards providing a laminate through hole in physical communication with an air vent and a vacuum source to promoting flow of underfill from each edge of a semiconductor chip simultaneously. Further, Akram et al. is not concerned with intentionally creating excessive underfill at a through hole exit to eliminate voids and cleaning and sealing the through hole in the manner of the present invention.
DiStefano et al. disclose, in U.S. Pat. No. 6,653,172 B2, issued Nov. 25, 2003, methods for providing substantially void-free layers for semiconductor assemblies. DiStefano et al. disclose providing an interposer layer between such a fluid encapsulant between a semiconductor chip and a substrate so that voids within the interposer layer are sealed after applying pressure simultaneously to the voids. However, DiStefano et al. is not directed towards providing a laminate through hole in physical communication with an air vent and a vacuum source to promoting flow of underfill from each edge of a semiconductor chip simultaneously. Further, DiStefano et al. is not concerned with intentionally creating excessive underfill at a through hole exit to eliminate voids and cleaning and sealing the through hole in the manner of the present invention.
In order to combat the issue of voids, Hong et al., discloses in U.S. Pat. No. 6,895,666 B2, issued May 24, 2005, an underfill system for a semiconductor package. The underfill system uses a nozzle to dispense underfill resin into a gap between semiconductor chips and substrates. The gap is filled with the underfill resin due to a pressure difference between a main duct and a plurality of sub-ducts that occurs when a blower blows air through the main duct causing suction of the underfill from the sub-ducts. The invention of Hong et al. provides for shortened filling time of the underfill process and prevents voids (i.e. air bubbles) of the filling material from forming within the gap.
However, Hong et al. is not directed towards providing a laminate through hole in physical communication with an air vent and a vacuum source to promoting flow of underfill from each edge of a semiconductor chip simultaneously. Further, Hong et al. is not concerned with intentionally creating excessive underfill at a through hole exit to eliminate voids and cleaning and sealing the through hole in the manner of the present invention.
Further, none of the prior art inventions resolve the issue of preventing over spreading of the underfill material. However, each of these solutions encounters significant problems. One problem is the residual void occurring in underfill resin is not eliminated in a low cost manner. The difficulty in the void control contributes to a significant increase in manufacturing costs in light of the prior art. Another problem is there is a long process time for resin leveling. Further, the inefficient and time-consuming prior art underfill techniques also cause undue and significant increases in the manufacturing costs. None of the prior an attempts resolve the problem caused by excessive resin underfill.
Despite these and other efforts in the art, still further improvements in enabling quicker underfill spread, reduction of voids and optimal management of excessive resin underfill would be desirable.